Fireplace hot air furnace



June 12, 1956 JOHNSON 2,749,905

FIREPLACE HOT AIR FURNACE Filed Oct. 14, 1952 2 Sheets-Sheet l INVENTOR. AND e E w L. Jay/v50 A T Toe/vs VJ June 12, 1956 A. L. JOHNSON FIREPLACE HOT AIR FURNACE 2 Sheets-Sheet 2 Filed Oct. 14. 1952 INVENTOR. A/voesw L- Joy/v50 BY WZ WfiW Mid/warm ATT ENEYJ //X/ 1/ 1 I A 1/ FIREPLACE HOT AIR FURNACE Andrew Lager Johnson, Douglas, Wyo.

Application ()ctober 14, 1952, Serial No. 314,649

2 Claims. (Cl. 126-121) This invention relates to hot air circulating heaters or furnaces and more particularly to a hot air furnace mounted in a fireplace to heat one or more rooms adjacent the fireplace.

It is among the objects of the invention to provide an improved hot air circulating heater which can be built into a fireplace and chimney structure and provides an internal form which facilitates building the fireplace portion of the structure; which is adapted to use various kinds of fuel, such as wood, coke, coal, oil, and gas; which can be used to heat one or more rooms adjacent the fireplace and provides for adequate circulation of hot air in the room or rooms without the admission of any smoke or combustion products thereto; which has a check draft damper for controlling the operation of the furnace and the heating and ventilation of the adjacent space; which is substantially concealed from view when built into a fireplace and enables the fireplace to present a substantially conventional appearance; which is constructed to withstand high temperatures for a long period of time; and which is simple and durable in construction, economical to manufacture and install, and efficient and effective in operation.

Other objects and advantages will become apparent from a consideration of the following description and the appended claims in conjunction with the accompanying drawings wherein:

Figure l is a front elevational view of a hot air circulating heater illustrative of the invention;

Figure 2 is a side elevational View of the heater illus trated in Figure 1;

Figure 3 is a cross sectional view on the line 33 of Figure 1;

Figure 4 is a cross sectional view on the line 4--4 of Figure 2; and

Figure 5 is a cross sectional view on the line 5-5 of Figure 3.

Figure 6 is an enlarged fragmentary sectional view of the lower left-hand portion of Figure 3.

With continued reference to the drawings, the hot air circulating heater comprises an outer casing, generally indicated at 10, of substantially rectangular shape having a front wall 11, a back wall 12, side walls 13 and 14, and a top wall 15.

The back Wall 12 is a flat body of rectangular shape, prferably formed of suitable material, such as steel boiler plate, and is disposed in substantially vertical position when the heater is operatively installed in a chimney and fireplace structure.

The front Wall 11 has in its lower portion a rectangular opening of the size of the desired firplace opening which opening extends from one of the side walls to the other, and the front wall has above the opening 16 an upwardly and inwardly directed flange portion 17 providing a support for the masonry structure immediately above the fireplace opening and includes a fiat portion 18 inclined inwardly and upwardly from the inner edge of the flange portion 17 to a location above and spaced from the front edge 2,749,905 Patented June 12, 1956 r Ice of the top wall 15. A hood or duct 19 extends from the upper edge of the front wall portion 18 substantially to the plane of the back Wall 12 and is inclined upwardly and rearwardly and spaced above the top wall 15 to provide a duct or passage for products of combustion, the rear end of this hood 19 being connected through a passage 24) to an upwardly extending chimney flue, not illustrated.

The side walls 13 and 14 are also flat bodies of suitable material, such as boiler plate, and are disposed substantially perpendicular to the back Wall 12, one at each edge of the latter, and are substantially vertically disposed when the heater is in operative position.

The top wall 15 is downwardly and forwardly inclined from the upper edge of the back wall 12 and has its front edge spaced from the inclined portion 18 of the front wall of the outer housing, as explained above, and a partition wall 21 is disposed in the outer housing and is spaced forwardly from and substantially parallel to the back Wall 12. This partition wall extends from a location adjacent the front edge of the top wall 15 downwardly to a location spaced above the bottom edges of the side walls 13 and 14, and is connected at its top edge to the front edge of the top wall and along its side edges to the side walls 13 and 14 of the outer housing.

The partition wall 21 is preferably of heat insulating construction and may conveniently comprise two bodies 22 and 23 of sheet or plate metal disposed in parallel relationship with a flat body 24 of heat insulating material therebetween, the bodies 22 and 23 being secured together by bolts 25 extending through registering apertures in the two sheet metal bodies and in the body of insulating material at locations spaced apart over the area of the partition wall 21. A plate 26 depending from the front edge of the top Wall 15 to the upper end of the partition wall 21 connects the partition wall to the front edge of the top Wall.

A combustion chamber, generally indicated at 30, is disposed between the back wall 12 and the partition Wall 21 of the heater and is spaced from and substantially parallel to both of these walls of the outer housing. This combustion chamber comprises an outer housing 31 of rectangular shape having an open bottom end and having its upper end partly closed by a top wall 32 leaving a vent opening 33 along the rear side of the upper end of the combustion chamber. The combustion chamber further includes an inner casing 35, also of rectangular shape, having a top wall 36 spaced downwardly from the top wall 32 of the outer housing of the combustion chamber and having a trough shaped bottom wall 37 spaced above the bottom end of the outer firebox housing 31. The side or face walls of the inner casing 35 are spaced from and substantially parallel to the side or face walls of the outer housing 30, but are connected along their side edges to the side walls of the outer housing 30 and these side Walls are provided with openings, the edges of which extend around the corresponding edges of the side, top and bottom walls of the inner housing 35, so that a passage isprovided through the combustion chamber extending width-Wise of the combustion chamber and of a size and shape corresponding to the size and shape of the interior of the inner housing 35 on a substantially vertical plane disposed perpendicular to the side or face walls of the inner casing and the outer housing of the combustion chamber 30.

The back wall of the outer housing of the combustion chamber 30 extends above the upper edge of the front wall of this housing and this upwardly extending portion of the back wall together with an upward extension along the inner edge of the top Wall 32 of the combustion chamber provides a neck 37a extending upwardly from the upper end of the combustion chamber at the rear or back side of the latter, and a horizontally disposed duct 38 extends from the upper end of this neck through an aperture in the partition wall 21 of the heater to provide a passage for combustion products out of the combustion chamber and into the space between the partition wall 21 and the front wall 11 of the outer housing of the heater above the fireplace opening 16.

The back wall 31 of the combustion chamber is extended downwardly by a plate extension 40 to the plane of the bottom edges of the side walls 13 and 14, and the bottom end of the inner housing 35 of the combustion chamber is disposed above the plane of the bottom edges of the side walls 13 and 14 a distance such as to form a firebox in which a gas or oil burner can he placed adjacent the extension 40 and below the bottom wall 37 of the inner casing 35.

The bottom edge of the front wall of the combustion chamber outer housing is disposed above the plane of the bottom edges of the side walls 13 and 14 of the outer housing of the heater and a horizontally disposed plate 41 extends from the bottom edge of the front wall of the combustion chamber to the bottom edge of the partition wall 21 of the heater and is joined to both of these walls to provide an airtight connection therebetween. The plate 41 extends from one of the side walls 13 or 14 to the other and a flange 42 depends from the plate 41 near the front edge of this plate and is disposed above the plane of the bottom edges of the side walls 13 and 14 to provide an opening 43 leading from the front portion of the outer housing of the heater into the lower end of the combustion chamber 30.

The partition wall 21 is detachably secured to the structures 26 and 41 and to the side walls 13 and 14 by suitable means, such as the bolts 62, so that this wall can be easily removed to provide access to the combustion chamber 30.

In use, the hot air circulating heater is mounted on a suitable hearth in the fireplace portion of the fireplace and chimney structure, and the opening 43 provides a draft opening for combustion air when a fuel oil or gas burner is mounted on the hearth adjacent the extension 40 of the back wall of the combustion chamber. When the heater is used to burn coal or coke, a suitable basket type grate is mounted in the front portion of the outer housing 10 between the side walls 13 and 14 and immediately in front of the partition wall 21 and the opening 43 provides a passage for heat and combustion products from the coal or coke burning in the basket grate into the interior of the combustion chamber 30.

When wood is burned in the heater, a pair of andirons may be placed on the hearth or floor immediately in front of the partition wall 21 and the heat and products of combustion from the burning wood will then be drawn through the opening 43 and into the bottom end of the combustion chamber 30 of the heater.

While the various fuels, as indicated above, may be used, it has been found that the heater operates with particularly high efficiency when gas is used as the fuel and a gas burner is disposed below the bottom end of the inner housing 35 in the firebox.

A horizontally disposed plate 44 extends from the bottom edge of the back wall of the outer housing 31 of the combustion chamber to the bottom edge of the back wall 12 of the outer housing of the heater and provides an airtight connection between the combustion chamber and the back wall of the heater. The plates 41 and 44 thus close the bottom ends of the spaces between the back wall 12 and the partition wall 21 and the adjacent sides of the combustion chamber 30 which spaces together with the passage through the combustion chamber provided by the inner housing 35 constitute air heating passages within the heater adjacent the combustion chamber 30.

The side wall 13 is provided with a lower Opening 45 adjacent the lower edge thereof and with an upper opening .46 adjacent the upper edge thereof, and the side wall 14 is provided with similar lower and upper openings 47 and 48. Air inlet ducts i9 and 5 9 are connected at their ends to the side Walls 13 and 14 at the outer sides of the side walls and in surrounding relationship to the openings 45 and 47 and air outlet ducts 51 and 52 are secured at their ends to the side Walls 13 and 14 respectively, at the outer sides of these side walls and in surrounding relationship to the openings 46 and 48, so that cold air may enter the air heating space or passages described above, flow upwardly past the combustion chamber 3t) and out of the air heating space through the openings 16 and and the eucts 51 and 52. The ends of the air intake and air outlet ducts remote from the side walls 13 and 14 are connected into a room or space to be heated to provide a circuiation of heating air in the room or space.

Gbviously, suitable fans or blowers, as indicated at 64, may be provided in the outlet ducts 51 and 52, if desired, .-r found necessary, to increase the circulation of hot air .bc-ve the circulation provided by convection, and additional air inlet and outlet duets with suitable openings may be provided, if found desirable, or necessary. For example, an air inlet and an air outlet duct could be extended through the back wall 12 of the outer housing to heat a room adjoining the fireplace, if the fireplace is provided in an interior wall of a building.

A check draft damper 54 comprising a metal plate of elongated rectangular shape, is disposed in the space between the upper portion 11 of the front wall of the outer housing and the partition wall 21. This damper is mounted along one edge on a rod 55 which is disposed adjacent and substantially parallel to the inner edge of the flanged portion 17 of the front wall and extends at its ends through apertures in the side walls 13 and 14 and the damper extends from the rod 55 toward the partition wall 21, so that its edge remote from the rod 55 is substantially in contact with the outer surface of the partition wall when the damper is closed, as illustrated in Figure 3. A control lever 56 is connected at its upper end to the damper 54 and depends therefrom adjacent the inner side of one of the side walls 13 or 14 and a notched rack or quadrant 57 is mounted on the inner side of the corresponding side wall and engages the lower end of the damper control lever 56 to hold the damper in selected positions of angular adjustment about the axis of the hinge rod 55.

When the heater is used to burn gas or oil the damper 54 will preferably be left in its closed position at all times, although it may be opened if the temperature in the space heated by the heater reaches an uncomfortably high value or if it is desired to provide extra ventilation. However, when the heater is used to burn solid fuel in front of the partition wall 21, the damper 54 is fully opened before such solid fuel is ignited, so that the smoke and fumes, generated by the combustion of the fuel before a normal burning rate of combustion is obtained, can be directed upwardly between the front wall and the partition wall of the outer housing and will not pass from the fireplace heater into the adjoining space to be heated. The damper should also be opened when additional solid fuel is being added to the fire. While the solid fuel is burning at a normal rate of combustion, the damper 5 may be closed to any degree consistent with nonsmoking operation of the heater, so that all, or the major portion of the heat and combustion products from such solid fuel will be drawn through the opening 43 into the bottom end of the combustion chamber 30. When solid fuel is being used, the damper may also be controlled to regulate the temperature and ventilation of the heated space.

The hot air circulating heater of the present invention is of a simple shape that is easy to incorporate into a fireplace and chimney structure and, when building the fireplace and chimney, upon completion of the hearth, the heater is placed on the hearth in proper position and the masonry work continued upwardly, using the outer housing of the heater as an inner form to facilitate laying up the masonry construction. As the outer housing of the heater has its outer surface disposed directly against the masonry structure and as this masonry structure willinclude firebrick, as indicated at 60, at the outer side of any portion of the heater subjected to high temperatures, the outer housing may be formed of a much thinner sheet material than that of the combustion chamber 30 which is subjected to the flame temperature of the burning fuel.

Because of the large area of the combustion chamber contacted by the circulating air and the inner passage through the combustion chamber, the maximum amount of heat is absorbed by the circulating air from the combustion chamber and from the burning fuel and combustion products thereof, so that the device operates with a high degree of fuel efiiciency, and because of the large inlet and outlet openings located at the bottom and top ends of the combustion chamber, a maximum circulation of heated air is maintained.

The invention may be embodied in other specific forms without departing from the spirit or essential character istics thereof. The present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims, are therefore, intended to be embraced therein.

What is claimed is:

1. In combination, a fireplace having a flue at its upper end, a hot air furnace disposed in said fireplace, said furnace comprising an outer casing having a back wall, side walls, and a top wall sloping downwardly from the back Wall and joined to the top edges of said side walls, and a front wall joined to the upper front edge portions of the side walls and terminating above the base of said fireplace to form with the side walls a fireplace opening, said front wall having above the opening a flat portion' inclined inwardly and upwardly to a location above and spaced from the front edge of said top wall, a hood inclined upwardly and rearwardly from the upper edge of the inclined fiat portion of said front wall to substantially said back wall and providing a passage for products of combustion, a partition wall dependingly carried by said top wall adjacent the front ends thereof and having its lower end spaced above the base of said fireplace, a combustion chamber positioned between said casing back wall and said partition wall, said combustion chamber including a space at the lower end and forming a firebox-for the accommodation of a heating source therein, said firebox being in communication with the spaced lower end of the partition wall, the combustion chamber including an outer housing positioned above the firebox and an inner casing within said outer housing and spaced from the latter, the space between said inner casing and outer housing providing another passage having the lower end in communication with said firebox, an outlet duct in the upper end of said another passage and in communication with said first named passage above the fireplace opening, and ducts in the side walls of said outer casing for admitting air into said air heating passages.

2. In combination, a fireplace having a flue at its upper end, a hot air furnace disposed in said fireplace, said furnace comprising an outer casing having a back wall, side walls, a top wall sloping downwardly from the back wall and joined to the top edges of said side walls, and a front wall joined to the upper front edge portions of the side walls and terminating above the base of said fireplace to form with the side walls a fireplace opening, said front wall having above the opening a flat portion inclined inwardly and upwardly to a location above and spaced from the front edge of said top wall, a hood in clined upwardly and rearwardly from the upper edge of the inclined fiat portion of the front wall to substantially said back wall and providing a passage for products of combustion, a partition Wall dependingly carried by said top wall adjacent the front end thereof and having its lower ends spaced above the base of the fireplace, a combustion chamber positioned between said casing back wall and said partition wall, said combustion chamber including a space at the lower end and forming a firebox for accommodation of a heating source therein, said firebox being in communication with the space at the lower end of said partition wall, the combustion chamber including an outer housing positioned above said firebox and an inner casing Within said outer housing and spaced from the latter, the space between said inner casing and outer housing providing another passage having the lower end in communication with said firebox, an outlet duct in the upper end of said another passage and in communication with said first named passage above the fireplace opening, ducts in the side walls of said outer casing for admitting air into said air heating passages, and an adjustable check draft damper disposed in the space between the inclined fiat portion of said casing front wall and the adjacent portion of said partition wall.

References Cited in the file of this patent UNITED STATES PATENTS 1,756,511 Dowler Apr. 20, 1930 2,181,624 Maurer Nov. 28, 1939 2,471,351 Russell May 24, 1949 2,484,292 Hermanson Oct. 11, 1949 

